I see 2 options available in this kind of situations
1) Have a meeting with the Project Manager who is not performing well and let him know of the areas where he needs to improve on. Together find a way to keep track of his performance in order to avoid him derailing the project again. I suggest a daily standup call with him.
2) If you cannot improve a bad gear in the system you will have to replace it. If the PM does not seem to improve find a better Project Manager.
Hope this helps,